A mutant E.coli strain, grown under conditions that normally induce the lac operon, produces high amounts of $\beta$-galactosidase.What is a possible genotype of the cells? A)lacI⁺ lacP⁺ lacO⁺ lacZ^- lacY⁺ lacA⁺ B)lacI⁺ lacP⁺ lacO^c lacZ⁺ lacY⁺ lacA⁺ C)lacI^- lacP⁺ lacO⁺ lacZ^- lacY⁺ lacA⁺ D)lacI⁺ lacP^- lacO⁺ lacZ⁺ lacY⁺ lacA⁺ E)lacI^- lacP^- lacO⁺ lacZ^- lacY⁺ lacA^-

Question

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The mutant E.coli strain is producing high amounts of β-galactosidase under conditions that induce the lac operon. This indicates that there may be a mutation in the regulatory region of the lac operon (lacI) or there may be a mutation in one of the structural genes of the operon (lacZ, lacY, or lacA). Additionally, the presence of the F1F1F1S1 sequence suggests that there may have been a frameshift mutation in the lacZ gene. Choice B is the best option as it has a mutation in the lacZ gene (lacZ⁺) which could cause high levels of β-galactosidase production. It also has mutations in the lacI and lacO regions, which could affect regulation of the operon. The other choices either have mutations in genes that are not directly involved in β-galactosidase production or do not have a frameshift mutation in the lacZ gene which is indicated by the F1F1F1S1 sequence.

A Mutant E β\betaβ -Galactosidase

A Mutant E $\beta$ -Galactosidase